Windmill or Wind Turbine- powered boats: how many are out there, and are they viable?

[Guest625101138]

Originally Posted by Windmaster

Yes of course, I certainly understand that it is just something you put together quickly to try an idea.
But when I said "have you considered" I really meant "do you think its a good idea" - just wanted to get your opinion about finding a way to make it more safe and reliable since you mentioned that it was difficult to control.

The low area, high aspect blades are the best option without going to the complexity of pitch adjustment. They will give the highest efficiency. This means they offer the least drag for the power output.

In setting up for this first test I took shortcuts that made control difficult. My original idea for the turbine angle control was a large diameter spoked wheel that was easy to reach through the entire rotation. The problem with this is that it would make the turbi-prop difficult to transport. Hence I produced a control lever that could be locked and unlocked with the intention of inching the turbine through the wind as I turned the boat. In the conditions this was impractical. I need to make a control wheel that can be easily assembled on the turbine mast. I do not want the turbine to weather vane because I then have no means of depowering.

I intended to fair the underwater portion of the unit on Sunday but I had time constraints imposed by other obligations that limited time. In the circumstances it was a serious flaw. Often the prop was doing violent stirring rather than actually propelling. The fairing will also act as a deep keel and improve steering.

I selected the prop with a low pitch to ensure it would work in light conditions. Given the ease it progressed to windward I should be able to run the 625mm pitch prop I have. This will get higher speed at lower revs. If the prop does not aerate this will calm things down although the thrust on the blades could be a little higher.

The boat is set up for pedalling. The outriggers mounting it light and flimsy. If I stiffen these a strut I can more confidently load them up and also set them up so they do not flex.

So there are a few things to tweak before the next test. If it is really windy I will use the aluminium cat but it does not have the same speed potential of the V11 hull.

Rick W

[Windmaster]

Originally Posted by Rick Willoughby

So there are a few things to tweak before the next test. If it is really windy I will use the aluminium cat but it does not have the same speed potential of the V11 hull.

Rick W

Well I guess it's a development process. I hope you can get a good improvement from your modifications. Be nice if you can get someone to film it from the shore. Then you can put it on Youtube. At the moment there are only two working wind-turbine boats on there. My own, and the other bigger boat built by Jim Wilkinson and operated out of Guernsey in the Channel Islands. Incidently, you can find it by searching for "unusual catamaran". I don't think Jim Wilkinson is a member of this forum though.
Incidently, "turbi-prop" is quite a good name for these kind of boats.

[backyardbil]

Hi Windmaster

If your video on Youtube is the one under "Windmill Driven Boat" its quite interesting. The pitch control certainly stops the wind-turbine quickly! I see that the film is marked 1995 - do you still have this boat? Also looked under "unusual catamaran" and found the other boat.

Bil

[Windmaster]

Bil

I don't still have the boat but I still have the "running gear" i.e. the rotor head, pitch control mechanism blades etc. I intend to mount them on a 16ft Prindle cat that I have. As you probably saw from the video the boat used (12ft) was a little small.

I'm really trying to develop a boat to use on the local rivers here in Norfolk, we have about 150 miles of navigable rivers, but they are winding and sometimes tree-lined. The wind comes from all over the place and this is why I used a weathercocking rotor head which instantly swings round for wind changes. The old wherrymen used to say "the wind follows the river" - I didn't believe that but after sailing round here I realised that the wind was dead ahead a disproportional amount of the time. That's why I'm still interested in the "direct into wind" boat. Since there is often no room to tack, either because of other traffic or the narrowness of the waterway.

I'm really interested to see if Rick's approach (fast high-speed rotor) is better than mine (high solidity sloooooow turning). If he can do it better, then hats off to him. His is based on theory and mine is based on testing. Perhaps he can explain theoretically why the slow turning system works better.

But whatever happens I think the slow turning wind turbine is less likely to "chop you up" than a two-blader whipping round at 500 rpm! Due to the number of blades - 6 or 8 on my turbines - the appearance is that they are going round at high-speed. But look carefully and you'll see that the speed is really quite slow. Less than 100rpm!

As a matter of fact I found an interesting page about that today. http://www.solarnavigator.net/windmill_efficiency.htm

It's not all correct, but it is certainly worth looking at.

[srimes]

Originally Posted by Windmaster

Bil

As a matter of fact I found an interesting page about that today. http://www.solarnavigator.net/windmill_efficiency.htm

It's not all correct, but it is certainly worth looking at.

Looks to me like he's a little crazy. Energy is mis-defined? Power=force? WTF?

You can't just re-define these basic concepts to suite your ideals. I don't think he understands what efficiency is as well.

That said, there IS a place for high blade count low rpm windmills. They have higher starting torque and are good for pumping water.

[backyardbil]

Rick

Did you do any further testing of your wind-turbine boat
?

[Guest625101138]

Originally Posted by backyardbil

Rick

Did you do any further testing of your wind-turbine boat
?

Yes. The transmission problem was that a grub screw had worked loose so an easy fix.

I made a 6ft diameter spider wheel to control the angle of the turbine and this worked reasonably well.

The breeze was variable and quite strong at times but not enough to capsize me and I could depower if I needed.

I went to a 625mm pitch on the prop and this gave mixed results. I needed better than 20 to 25kph wind to go directly into the wind and it was no faster than last week. When reaching it was much faster with the higher pitch. Also nice going downwind. In sustained strong wind I may have got a better speed up wind but it was too flukey to get moving steadily. I ended up losing ground so had to carry the boat back up the lake. Last week I could easily make way to windward but the wind was also stronger.

In 10 to 20kph the wind was enough to spin the turbine but the prop area was too small to get sufficient grip. Hence the boat went slowly backward. In a sustained gust the turbine would wind up and the boat would start moving forward.

My photographer had to get to his footy match so still no video to show. The ideal pitch for fixed gearing would be around 500mm but the best would be variable ratio transmission.

For now I will go back to the 300mm pitch prop and hopefully get some on-water video in the coming weeks. The photgrapher is at the end of his footy season so will have more time soon.

Rick

[backyardbil]

Rick

Very interesting report - look forward to your next tests. Thanks for letting us know how you got on.

[backyardbil]

I have been looking at the website for the "Aeolus" wind energy event which has been held in Holland. http://www.windenergyevents.com/

It doesn't look as if the craft are self-starting - most of the films show that they start off by being pushed, or running down a slope in some cases.

Incidently, I have noticed that they have cancelled this year's event due to the withdrawal of a major sponsor.

[MPraamsma]

Hello BB,

Yes, the event has been cancelled for this year due to the economy etc, but will be held next year 2010. I plan to enter a vehicle if I am able to get some sponsorship etc. The cars are not required to be self starting, but allow a push of 50 meters from team members. My car will never be self starting, because it uses a duct to amplify the flow rate, and that depends on vehicle motion to create. They are flexible about many things still at this point because they don't want to make things too difficult. In my case, the car would benefit from actually having an electrical starting mechanism to get things going because the fan turns at a very high RPM, and needs to get to a minimum speed before the foils 'take off', just like airplanes don't fly under 60 MPH. I think at this point the rules can be negotiated since it is very early in the game and no one knows where this will all lead.

[Windmaster]

MPraamsma

That's a very interesting prospect and I don't know of any others that use or propose to use a duct. I can't really visualise what it will look like - do you have a drawing of the complete vehicle? It's obviously not secret if you intend to use it in public.
I would certainly be very interested to hear more about any model testing you have done.

Windmaster

[MPraamsma]

Windmaster,

Actually, I am keeping what I am doing under wraps a little for now, but I can tell you a few things about it. I probably shouldn't even be concerned about someone trying to copy it, because typically you can't even GIVE radical ideas away. However I have protected it just in case.

I seem to remember you read my earlier posts, and have a good idea of the direction I was going in. As I mentioned before, the problem as I saw it was the creation of what I termed 'adverse thrust' which worked counter to the thrust developed at the wheel/road (prop/water) interface. I outlined a way to get around this by installing the fan in a duct with stator blades to force the flow to strike the blade at an angle that tilted the resultant vector so that it coincided with the tangential axis of the turbine. A small amount of the lift was used to offset the drag, so in theory no axial thrust developed (review my old posts to catch up).

In another epiphonous moment, I concluded that by tapping off a small amount of power from the tubine, and running it back up to a prop ahead of the turbine but still in the duct, would allow the flow to be augmented and flow through the duct even faster. This is turbo-jet thinking, but in this case the turbine is many times larger than the compressor (the opposite of a conventional TJ) This also makes sure that the duct has an active vacuum and not a passive vacuum (from a simple free flowing venturi).

Furthermore, the flow would also be forced to pass through a thin annular opening so that the blades would be short and plentiful. However, still being concerned about some residual adverse thrust, I reasoned that it would also be advantageous to turn the entire turbine so that it would be spinning in the horizontal plane, that way any forces would be unable to effect the plane in which the vehicle is translating. In other words, it could only add lift or downforce to the vehicle, but could not retard its progress.

As I was toying with the idea and seeing how narrow I could make the annular passage, it suddenly dawned on me, why not just take the entire flow and turn it so it flows through a squirral cage style turbine, then all adverse thrust would be cancelled completely within the machine. At the moment the flow passes over the turbine blades it is moving perpendicular to the direction of vehicle motion, so it cannot by definition affect that axis.

Then I had to take the biggest leap of faith of all, and turn the flow 180 degrees and go around the edge of the turbine and head INTO the turbine on the other side. There it encounters another set of blades that are configured facing the other way, and extract power again (the angle of attack is obviously greater on the second set). Of course, where the flow goes around the edge is the actual venturi of the system.

Suddenly the symetry of the whole thing hit me like a ton of bricks. If a prop on the inlet can augment the flow by 'pushing' it through, then why not add one more on the exit that pulls the flow as well. That way there is a 'push-pull' effect to make sure the venturi doesn't get lazy and stall. Therefore, a second prop makes sure the system can adequately discharge the flow and restore it to the ambient field.

Of course I still need stators to hold the whole thing in place, and these then serve to create a swirl on the inlet, and to recover thrust on the exit. The result was a rather unlikely and even more counter-intuitive design, where the entire flow entering the duct (the total frontal area of the vehicle) passes at the local speed of sound through a very narrow slit. Because the annulus is fairly large in diameter, the area is actually pretty big.

This arrangement is very compact compared to the normal wind tubine, so it needs to be fed air from a larger passive portion of the venturi duct. This means that it is useless when standing still, because then it would need to suck air in, and that is not the point. It needs the motion of the vehicle to jam air into the inlet so the mass flow is as high as possible.

The Aeolus rules allow an area of 4 square meters, but in this case that would be too much air, so I have kept it down to exactly one square meter, so that it would be easier to calculate everything. I am adding an abreviated diagram to illustrate all of this, so let me know if this seems logical to you. If you want I can elaborate, but I am curious what you see in it so far.

[Windmaster]

Mpraamsma

You say you want to keep your idea under wraps but you then give a very full description of it!
Well, you have explained theoretically how it could work and to be honest I don't have the technical expertise to say what you propose is valid or not.
It is certainly true that the main barrier to overcome in trying to go directly to windward is as you say "adverse thrust" and I take your point that you can divert the air to go in another direction with stators, but what about the force on the stators caused by the diversion?
What you describe is a very interesting thought experiment, but do you have any evidence that it is going to work in real life? Any experimental data?
It's quite complicated and if you intend to get it working by 2010 you need to start now.
If the Aeolus rules allow 4 square meters then I think it would be counter productive to use less.
In the final analysis the amount of power you can collect will depend upon HOW MUCH AREA OF WIND YOU CAN INTERCEPT.
Obviously the organisers sense that is the case and that is the reason they chose an upper limit. To say that 4 square meters is "too much air" and you want to reduce it to 1 square meter means that you reduce your power by 75percent whatever way you collect it.
Don't forget even if you take away the "adverse force" from the turbine you still have the drag force from the vehicle body, wheels, and support structures to overcome. Reducing the power by 75 percent does not seem a good way to start doing this.

[MPraamsma]

Windmaster,

As I said, even giving away new concepts is harder than it seems. The Aeolus rules allow 4 square meters, but a maximum width of 2 meters, so a little math will show that a single rotor 2 meters wide is only 3.14 (Pi) square meters. There is a lot more to my design than I have shown at this point, and one square meter already fills the allowable width when wheels and suspension are included. Also, the size of the fan would be beyond my technical resources to construct if it were much bigger. Already the rotor is around 60 cm in diameter and turns at thousands of RPM. At a speed of 50 KPH that also means that around 15 cubic meters of air passes through the duct each second. Proving a concept and winning a race are separate issues for me, the former is my goal, the latter would be icing on the cake. I already proved with my bicycle set-up that 11-12 MPH is the absolute top speed of a normal fan because of adverse thrust. My test bike had pedals as well, so I could feel the results perfectly in my legs while testing it. I'm looking for a method that breaks through that barrier, and better gears, variable props etc. will just not do the trick. I have been working on this concept for over 30 years, and only recently was I able to see where the problem was.

[Windmaster]

MPraamsma

All I can say is good luck to you and I hope you can both prove your point and win the race! If you've been working for 30 years then you do indeed deserve success.
I hope you can keep us informed on this forum of your progress.
If you feel you can reveal any further information, I for one, look forward to seeing it.